Scientists have unveiled an eighth planet orbiting a distant star in the solar system dubbed as Kepler-90, about 2,500 light years away from us.

The planet, Kepler-90i, was previously overlooked in the data from the Kepler Space Telescope as the signals were weak. But Google’s machine learning approach revisited the data and unearthed the hot rocky planet that orbits its star every 14.4 days.

The Kepler-90 planets have a similar configuration to our solar system with small planets found orbiting close to their star, and the larger planets found farther away. Credit: NASA/Ames Research Center/Wendy Stenzel

The artificial intelligence system allows computers “learn” – in this case to use the Kepler data. In this case, computers learned to identify planets from signals in the Kepler data that have traditionally been given a lower priority by the scientists sorting through it.

The system identifies exoplanets by looking at light readings recorded by Kepler and measuring minuscule change in brightness of when a star when a planet passed in front of it.

The Kepler Space Telescope has been searching in this way for planets outside our solar system – called exoplanets – since 2009 and previously discovered Kepler-90 in 2014.

NASA scientists have so far confirmed 2,525 exoplanets.

“Just as we expected, there are exciting discoveries lurking in our archived Kepler data, waiting for the right tool or technology to unearth them,” Paul Hertz, director of NASA’s Astrophysics Division in Washington, told reporters.

“This finding shows that our data will be a treasure trove available to innovative researchers for years to come.”

The Kepler-90 system plates travel in much tighter orbits than planets in our own solar system. structure of the Kepler-90’s system hints that the eight planets around Kepler-90 may have formed more spread out, like the planets in our own solar system, and then somehow migrated to the orbits we see them in today. Credit: NASA/Ames Research Center/Wendy Stenzel

The discovery makes the Kepler-90 system the only star system outside our own that has eight planets orbiting a single star. But the comparisons pretty much end there and the system would appear a poor chance of hosting life. Kepler-90 is about 20% bigger and 5% warmer than our Sun.

All eight planets orbit it at a much closer distance than the planets of our own system – seven of the eight would fit between Earth and the Sun instead of just Mercury and Venus.

Kepler-90i appears an inhospitable planet. It is about 30% larger than Earth, with an average surface temperature of about 430 °C, equivalent to that of Mercury.

About the Author

Bill Condie
Bill is former Head of Publishing at the Royal Institution of Australia. Previously he was Publisher of the popular science magazine, Cosmos, based in Melbourne, Australia. Bill has been a journalist for more than 30 years and his work has been published in Cosmos magazine, The Guardian, The Observer, The Times, The Daily Telegraph and the London Evening Standard.

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